1. Field of the Invention
This invention relates to a direct contact water heater or boiler having an internal combustion chamber wherein water to be heated comes into contact with a flame of the internal combustion chamber, and in particular to a direct contact water heater or boiler having an improved configuration for more uniform distribution of heat and water within the combustion chamber to facilitate and provide more efficient heat transfer.
2. Description of the Prior Art
Direct contact water heaters or boilers are water heaters in which water to be heated comes in contact with a flame or products of combustion located within a combustion chamber to provide heat transfer. These direct contact water heaters are usually of similar construction consisting of a tank or column in which a collection area or sump is provided at the lower end or bottom of the tank. Located above this is a combustion chamber which is provided with a burner unit. The burner unit produces a flame which is usually directed laterally within the combustion chamber. Above the combustion chamber is typically located a bed or section of packing material to provide increased surface contact for heat transfer. The packing material is formed from non-combustible, heat absorbing materials such as ceramic, metal or glass. Water to be heated is introduced at the top of the tank or column above the bed of packing material and is allowed to percolate to the combustion chamber. As the water percolates or cascades through the packing material, heat is transferred from the hot gasses of combustion and the packing material so that the temperature of the water is raised. The water is further heated as it passes through the combustion chamber itself to the sump where it is collected.
These prior art water heaters have many limitations. Because most direct contact water heaters utilize a laterally directed flame which may only partially fill the combustion chamber, only a portion of the water may actually come into contact with the flame as it passes through the combustion chamber. Thus, heat transfer is achieved primarily within the bed of packing material. The use of packing material is inefficient due to the higher amounts of energy are required to heat and maintain the temperature of the packings. The packings are also heavy and take up space which adds to the weight and size of the water heater.
It is the general object of the present invention to provide a water heater with improved contact of water with the flame within the combustion chamber for more efficient heat transfer and to eliminate the need for a bed of packing material.
Another object of the present invention is to provide such a direct contact water heater which is relatively simple in design and economical to manufacture.
Another object of the invention is to provide an improved heat source for such a direct contact water heater which combines the functions of prior art burner and flue gas collector components of such water heaters.